import java.util.HashMap;

class Solution {
    public String modifyString(String s) {
        char[] ss = s.toCharArray();
        int n = ss.length;
        for(int i = 0; i < n; i++) {
            if(ss[i] == '?') {
                for(char ch = 'a'; ch <= 'z'; ch++) {
                    if((i == 0 || ss[i-1] != ch) && (i == n-1 || ss[i+1] != ch )) {
                        ss[i] = ch;
                        break;
                    }
                }
            }
        }
        return String.valueOf(ss);
    }
}